summaryrefslogtreecommitdiff
path: root/include/linux/wait.h
blob: 5f3efabc36f4bb27af254bd7533e6c869bb68aaa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_WAIT_H
#define _LINUX_WAIT_H
/*
 * Linux wait queue related types and methods
 */
#include <linux/list.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>

#include <asm/current.h>
#include <uapi/linux/wait.h>

typedef struct wait_queue_entry wait_queue_entry_t;

typedef int (*wait_queue_func_t)(struct wait_queue_entry *wq_entry, unsigned mode, int flags, void *key);
int default_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int flags, void *key);

/* wait_queue_entry::flags */
#define WQ_FLAG_EXCLUSIVE	0x01
#define WQ_FLAG_WOKEN		0x02
#define WQ_FLAG_BOOKMARK	0x04

/*
 * A single wait-queue entry structure:
 */
struct wait_queue_entry {
	unsigned int		flags;
	void			*private;
	wait_queue_func_t	func;
	struct list_head	entry;
};

struct wait_queue_head {
	spinlock_t		lock;
	struct list_head	head;
};
typedef struct wait_queue_head wait_queue_head_t;

struct task_struct;

/*
 * Macros for declaration and initialisaton of the datatypes
 */

#define __WAITQUEUE_INITIALIZER(name, tsk) {					\
	.private	= tsk,							\
	.func		= default_wake_function,				\
	.entry		= { NULL, NULL } }

#define DECLARE_WAITQUEUE(name, tsk)						\
	struct wait_queue_entry name = __WAITQUEUE_INITIALIZER(name, tsk)

#define __WAIT_QUEUE_HEAD_INITIALIZER(name) {					\
	.lock		= __SPIN_LOCK_UNLOCKED(name.lock),			\
	.head		= { &(name).head, &(name).head } }

#define DECLARE_WAIT_QUEUE_HEAD(name) \
	struct wait_queue_head name = __WAIT_QUEUE_HEAD_INITIALIZER(name)

extern void __init_waitqueue_head(struct wait_queue_head *wq_head, const char *name, struct lock_class_key *);

#define init_waitqueue_head(wq_head)						\
	do {									\
		static struct lock_class_key __key;				\
										\
		__init_waitqueue_head((wq_head), #wq_head, &__key);		\
	} while (0)

#ifdef CONFIG_LOCKDEP
# define __WAIT_QUEUE_HEAD_INIT_ONSTACK(name) \
	({ init_waitqueue_head(&name); name; })
# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) \
	struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
#else
# define DECLARE_WAIT_QUEUE_HEAD_ONSTACK(name) DECLARE_WAIT_QUEUE_HEAD(name)
#endif

static inline void init_waitqueue_entry(struct wait_queue_entry *wq_entry, struct task_struct *p)
{
	wq_entry->flags		= 0;
	wq_entry->private	= p;
	wq_entry->func		= default_wake_function;
}

static inline void
init_waitqueue_func_entry(struct wait_queue_entry *wq_entry, wait_queue_func_t func)
{
	wq_entry->flags		= 0;
	wq_entry->private	= NULL;
	wq_entry->func		= func;
}

/**
 * waitqueue_active -- locklessly test for waiters on the queue
 * @wq_head: the waitqueue to test for waiters
 *
 * returns true if the wait list is not empty
 *
 * NOTE: this function is lockless and requires care, incorrect usage _will_
 * lead to sporadic and non-obvious failure.
 *
 * Use either while holding wait_queue_head::lock or when used for wakeups
 * with an extra smp_mb() like:
 *
 *      CPU0 - waker                    CPU1 - waiter
 *
 *                                      for (;;) {
 *      @cond = true;                     prepare_to_wait(&wq_head, &wait, state);
 *      smp_mb();                         // smp_mb() from set_current_state()
 *      if (waitqueue_active(wq_head))         if (@cond)
 *        wake_up(wq_head);                      break;
 *                                        schedule();
 *                                      }
 *                                      finish_wait(&wq_head, &wait);
 *
 * Because without the explicit smp_mb() it's possible for the
 * waitqueue_active() load to get hoisted over the @cond store such that we'll
 * observe an empty wait list while the waiter might not observe @cond.
 *
 * Also note that this 'optimization' trades a spin_lock() for an smp_mb(),
 * which (when the lock is uncontended) are of roughly equal cost.
 */
static inline int waitqueue_active(struct wait_queue_head *wq_head)
{
	return !list_empty(&wq_head->head);
}

/**
 * wq_has_sleeper - check if there are any waiting processes
 * @wq_head: wait queue head
 *
 * Returns true if wq_head has waiting processes
 *
 * Please refer to the comment for waitqueue_active.
 */
static inline bool wq_has_sleeper(struct wait_queue_head *wq_head)
{
	/*
	 * We need to be sure we are in sync with the
	 * add_wait_queue modifications to the wait queue.
	 *
	 * This memory barrier should be paired with one on the
	 * waiting side.
	 */
	smp_mb();
	return waitqueue_active(wq_head);
}

extern void add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
extern void add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
extern void remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);

static inline void __add_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
{
	list_add(&wq_entry->entry, &wq_head->head);
}

/*
 * Used for wake-one threads:
 */
static inline void
__add_wait_queue_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
{
	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
	__add_wait_queue(wq_head, wq_entry);
}

static inline void __add_wait_queue_entry_tail(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
{
	list_add_tail(&wq_entry->entry, &wq_head->head);
}

static inline void
__add_wait_queue_entry_tail_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
{
	wq_entry->flags |= WQ_FLAG_EXCLUSIVE;
	__add_wait_queue_entry_tail(wq_head, wq_entry);
}

static inline void
__remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry)
{
	list_del(&wq_entry->entry);
}

void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key);
void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
		unsigned int mode, void *key, wait_queue_entry_t *bookmark);
void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr);
void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode, int nr);

#define wake_up(x)			__wake_up(x, TASK_NORMAL, 1, NULL)
#define wake_up_nr(x, nr)		__wake_up(x, TASK_NORMAL, nr, NULL)
#define wake_up_all(x)			__wake_up(x, TASK_NORMAL, 0, NULL)
#define wake_up_locked(x)		__wake_up_locked((x), TASK_NORMAL, 1)
#define wake_up_all_locked(x)		__wake_up_locked((x), TASK_NORMAL, 0)

#define wake_up_interruptible(x)	__wake_up(x, TASK_INTERRUPTIBLE, 1, NULL)
#define wake_up_interruptible_nr(x, nr)	__wake_up(x, TASK_INTERRUPTIBLE, nr, NULL)
#define wake_up_interruptible_all(x)	__wake_up(x, TASK_INTERRUPTIBLE, 0, NULL)
#define wake_up_interruptible_sync(x)	__wake_up_sync((x), TASK_INTERRUPTIBLE, 1)

/*
 * Wakeup macros to be used to report events to the targets.
 */
#define poll_to_key(m) ((void *)(__force uintptr_t)(__poll_t)(m))
#define key_to_poll(m) ((__force __poll_t)(uintptr_t)(void *)(m))
#define wake_up_poll(x, m)							\
	__wake_up(x, TASK_NORMAL, 1, poll_to_key(m))
#define wake_up_locked_poll(x, m)						\
	__wake_up_locked_key((x), TASK_NORMAL, poll_to_key(m))
#define wake_up_interruptible_poll(x, m)					\
	__wake_up(x, TASK_INTERRUPTIBLE, 1, poll_to_key(m))
#define wake_up_interruptible_sync_poll(x, m)					\
	__wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, poll_to_key(m))

#define ___wait_cond_timeout(condition)						\
({										\
	bool __cond = (condition);						\
	if (__cond && !__ret)							\
		__ret = 1;							\
	__cond || !__ret;							\
})

#define ___wait_is_interruptible(state)						\
	(!__builtin_constant_p(state) ||					\
		state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE)		\

extern void init_wait_entry(struct wait_queue_entry *wq_entry, int flags);

/*
 * The below macro ___wait_event() has an explicit shadow of the __ret
 * variable when used from the wait_event_*() macros.
 *
 * This is so that both can use the ___wait_cond_timeout() construct
 * to wrap the condition.
 *
 * The type inconsistency of the wait_event_*() __ret variable is also
 * on purpose; we use long where we can return timeout values and int
 * otherwise.
 */

#define ___wait_event(wq_head, condition, state, exclusive, ret, cmd)		\
({										\
	__label__ __out;							\
	struct wait_queue_entry __wq_entry;					\
	long __ret = ret;	/* explicit shadow */				\
										\
	init_wait_entry(&__wq_entry, exclusive ? WQ_FLAG_EXCLUSIVE : 0);	\
	for (;;) {								\
		long __int = prepare_to_wait_event(&wq_head, &__wq_entry, state);\
										\
		if (condition)							\
			break;							\
										\
		if (___wait_is_interruptible(state) && __int) {			\
			__ret = __int;						\
			goto __out;						\
		}								\
										\
		cmd;								\
	}									\
	finish_wait(&wq_head, &__wq_entry);					\
__out:	__ret;									\
})

#define __wait_event(wq_head, condition)					\
	(void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
			    schedule())

/**
 * wait_event - sleep until a condition gets true
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 */
#define wait_event(wq_head, condition)						\
do {										\
	might_sleep();								\
	if (condition)								\
		break;								\
	__wait_event(wq_head, condition);					\
} while (0)

#define __io_wait_event(wq_head, condition)					\
	(void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
			    io_schedule())

/*
 * io_wait_event() -- like wait_event() but with io_schedule()
 */
#define io_wait_event(wq_head, condition)					\
do {										\
	might_sleep();								\
	if (condition)								\
		break;								\
	__io_wait_event(wq_head, condition);					\
} while (0)

#define __wait_event_freezable(wq_head, condition)				\
	___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,		\
			    freezable_schedule())

/**
 * wait_event_freezable - sleep (or freeze) until a condition gets true
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE -- so as not to contribute
 * to system load) until the @condition evaluates to true. The
 * @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 */
#define wait_event_freezable(wq_head, condition)				\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_freezable(wq_head, condition);		\
	__ret;									\
})

#define __wait_event_timeout(wq_head, condition, timeout)			\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      TASK_UNINTERRUPTIBLE, 0, timeout,				\
		      __ret = schedule_timeout(__ret))

/**
 * wait_event_timeout - sleep until a condition gets true or a timeout elapses
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, in jiffies
 *
 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * Returns:
 * 0 if the @condition evaluated to %false after the @timeout elapsed,
 * 1 if the @condition evaluated to %true after the @timeout elapsed,
 * or the remaining jiffies (at least 1) if the @condition evaluated
 * to %true before the @timeout elapsed.
 */
#define wait_event_timeout(wq_head, condition, timeout)				\
({										\
	long __ret = timeout;							\
	might_sleep();								\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_timeout(wq_head, condition, timeout);	\
	__ret;									\
})

#define __wait_event_freezable_timeout(wq_head, condition, timeout)		\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      TASK_INTERRUPTIBLE, 0, timeout,				\
		      __ret = freezable_schedule_timeout(__ret))

/*
 * like wait_event_timeout() -- except it uses TASK_INTERRUPTIBLE to avoid
 * increasing load and is freezable.
 */
#define wait_event_freezable_timeout(wq_head, condition, timeout)		\
({										\
	long __ret = timeout;							\
	might_sleep();								\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_freezable_timeout(wq_head, condition, timeout); \
	__ret;									\
})

#define __wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2)		\
	(void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 1, 0,	\
			    cmd1; schedule(); cmd2)
/*
 * Just like wait_event_cmd(), except it sets exclusive flag
 */
#define wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2)		\
do {										\
	if (condition)								\
		break;								\
	__wait_event_exclusive_cmd(wq_head, condition, cmd1, cmd2);		\
} while (0)

#define __wait_event_cmd(wq_head, condition, cmd1, cmd2)			\
	(void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
			    cmd1; schedule(); cmd2)

/**
 * wait_event_cmd - sleep until a condition gets true
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @cmd1: the command will be executed before sleep
 * @cmd2: the command will be executed after sleep
 *
 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 */
#define wait_event_cmd(wq_head, condition, cmd1, cmd2)				\
do {										\
	if (condition)								\
		break;								\
	__wait_event_cmd(wq_head, condition, cmd1, cmd2);			\
} while (0)

#define __wait_event_interruptible(wq_head, condition)				\
	___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,		\
		      schedule())

/**
 * wait_event_interruptible - sleep until a condition gets true
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function will return -ERESTARTSYS if it was interrupted by a
 * signal and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible(wq_head, condition)				\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_interruptible(wq_head, condition);		\
	__ret;									\
})

#define __wait_event_interruptible_timeout(wq_head, condition, timeout)		\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      TASK_INTERRUPTIBLE, 0, timeout,				\
		      __ret = schedule_timeout(__ret))

/**
 * wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, in jiffies
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * Returns:
 * 0 if the @condition evaluated to %false after the @timeout elapsed,
 * 1 if the @condition evaluated to %true after the @timeout elapsed,
 * the remaining jiffies (at least 1) if the @condition evaluated
 * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 * interrupted by a signal.
 */
#define wait_event_interruptible_timeout(wq_head, condition, timeout)		\
({										\
	long __ret = timeout;							\
	might_sleep();								\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_interruptible_timeout(wq_head,		\
						condition, timeout);		\
	__ret;									\
})

#define __wait_event_hrtimeout(wq_head, condition, timeout, state)		\
({										\
	int __ret = 0;								\
	struct hrtimer_sleeper __t;						\
										\
	hrtimer_init_on_stack(&__t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);	\
	hrtimer_init_sleeper(&__t, current);					\
	if ((timeout) != KTIME_MAX)						\
		hrtimer_start_range_ns(&__t.timer, timeout,			\
				       current->timer_slack_ns,			\
				       HRTIMER_MODE_REL);			\
										\
	__ret = ___wait_event(wq_head, condition, state, 0, 0,			\
		if (!__t.task) {						\
			__ret = -ETIME;						\
			break;							\
		}								\
		schedule());							\
										\
	hrtimer_cancel(&__t.timer);						\
	destroy_hrtimer_on_stack(&__t.timer);					\
	__ret;									\
})

/**
 * wait_event_hrtimeout - sleep until a condition gets true or a timeout elapses
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, as a ktime_t
 *
 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function returns 0 if @condition became true, or -ETIME if the timeout
 * elapsed.
 */
#define wait_event_hrtimeout(wq_head, condition, timeout)			\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_hrtimeout(wq_head, condition, timeout,	\
					       TASK_UNINTERRUPTIBLE);		\
	__ret;									\
})

/**
 * wait_event_interruptible_hrtimeout - sleep until a condition gets true or a timeout elapses
 * @wq: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, as a ktime_t
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function returns 0 if @condition became true, -ERESTARTSYS if it was
 * interrupted by a signal, or -ETIME if the timeout elapsed.
 */
#define wait_event_interruptible_hrtimeout(wq, condition, timeout)		\
({										\
	long __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_hrtimeout(wq, condition, timeout,		\
					       TASK_INTERRUPTIBLE);		\
	__ret;									\
})

#define __wait_event_interruptible_exclusive(wq, condition)			\
	___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,			\
		      schedule())

#define wait_event_interruptible_exclusive(wq, condition)			\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_interruptible_exclusive(wq, condition);	\
	__ret;									\
})

#define __wait_event_killable_exclusive(wq, condition)				\
	___wait_event(wq, condition, TASK_KILLABLE, 1, 0,			\
		      schedule())

#define wait_event_killable_exclusive(wq, condition)				\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_killable_exclusive(wq, condition);		\
	__ret;									\
})


#define __wait_event_freezable_exclusive(wq, condition)				\
	___wait_event(wq, condition, TASK_INTERRUPTIBLE, 1, 0,			\
			freezable_schedule())

#define wait_event_freezable_exclusive(wq, condition)				\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_freezable_exclusive(wq, condition);	\
	__ret;									\
})

/**
 * wait_event_idle - wait for a condition without contributing to system load
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_IDLE) until the
 * @condition evaluates to true.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 */
#define wait_event_idle(wq_head, condition)					\
do {										\
	might_sleep();								\
	if (!(condition))							\
		___wait_event(wq_head, condition, TASK_IDLE, 0, 0, schedule());	\
} while (0)

/**
 * wait_event_idle_exclusive - wait for a condition with contributing to system load
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_IDLE) until the
 * @condition evaluates to true.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 * set thus if other processes wait on the same list, when this
 * process is woken further processes are not considered.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 */
#define wait_event_idle_exclusive(wq_head, condition)				\
do {										\
	might_sleep();								\
	if (!(condition))							\
		___wait_event(wq_head, condition, TASK_IDLE, 1, 0, schedule());	\
} while (0)

#define __wait_event_idle_timeout(wq_head, condition, timeout)			\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      TASK_IDLE, 0, timeout,					\
		      __ret = schedule_timeout(__ret))

/**
 * wait_event_idle_timeout - sleep without load until a condition becomes true or a timeout elapses
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, in jiffies
 *
 * The process is put to sleep (TASK_IDLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * Returns:
 * 0 if the @condition evaluated to %false after the @timeout elapsed,
 * 1 if the @condition evaluated to %true after the @timeout elapsed,
 * or the remaining jiffies (at least 1) if the @condition evaluated
 * to %true before the @timeout elapsed.
 */
#define wait_event_idle_timeout(wq_head, condition, timeout)			\
({										\
	long __ret = timeout;							\
	might_sleep();								\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_idle_timeout(wq_head, condition, timeout);	\
	__ret;									\
})

#define __wait_event_idle_exclusive_timeout(wq_head, condition, timeout)	\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      TASK_IDLE, 1, timeout,					\
		      __ret = schedule_timeout(__ret))

/**
 * wait_event_idle_exclusive_timeout - sleep without load until a condition becomes true or a timeout elapses
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, in jiffies
 *
 * The process is put to sleep (TASK_IDLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 * set thus if other processes wait on the same list, when this
 * process is woken further processes are not considered.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * Returns:
 * 0 if the @condition evaluated to %false after the @timeout elapsed,
 * 1 if the @condition evaluated to %true after the @timeout elapsed,
 * or the remaining jiffies (at least 1) if the @condition evaluated
 * to %true before the @timeout elapsed.
 */
#define wait_event_idle_exclusive_timeout(wq_head, condition, timeout)		\
({										\
	long __ret = timeout;							\
	might_sleep();								\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_idle_exclusive_timeout(wq_head, condition, timeout);\
	__ret;									\
})

extern int do_wait_intr(wait_queue_head_t *, wait_queue_entry_t *);
extern int do_wait_intr_irq(wait_queue_head_t *, wait_queue_entry_t *);

#define __wait_event_interruptible_locked(wq, condition, exclusive, fn)		\
({										\
	int __ret;								\
	DEFINE_WAIT(__wait);							\
	if (exclusive)								\
		__wait.flags |= WQ_FLAG_EXCLUSIVE;				\
	do {									\
		__ret = fn(&(wq), &__wait);					\
		if (__ret)							\
			break;							\
	} while (!(condition));							\
	__remove_wait_queue(&(wq), &__wait);					\
	__set_current_state(TASK_RUNNING);					\
	__ret;									\
})


/**
 * wait_event_interruptible_locked - sleep until a condition gets true
 * @wq: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq is woken up.
 *
 * It must be called with wq.lock being held.  This spinlock is
 * unlocked while sleeping but @condition testing is done while lock
 * is held and when this macro exits the lock is held.
 *
 * The lock is locked/unlocked using spin_lock()/spin_unlock()
 * functions which must match the way they are locked/unlocked outside
 * of this macro.
 *
 * wake_up_locked() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function will return -ERESTARTSYS if it was interrupted by a
 * signal and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible_locked(wq, condition)				\
	((condition)								\
	 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, do_wait_intr))

/**
 * wait_event_interruptible_locked_irq - sleep until a condition gets true
 * @wq: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq is woken up.
 *
 * It must be called with wq.lock being held.  This spinlock is
 * unlocked while sleeping but @condition testing is done while lock
 * is held and when this macro exits the lock is held.
 *
 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 * functions which must match the way they are locked/unlocked outside
 * of this macro.
 *
 * wake_up_locked() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function will return -ERESTARTSYS if it was interrupted by a
 * signal and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible_locked_irq(wq, condition)			\
	((condition)								\
	 ? 0 : __wait_event_interruptible_locked(wq, condition, 0, do_wait_intr_irq))

/**
 * wait_event_interruptible_exclusive_locked - sleep exclusively until a condition gets true
 * @wq: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq is woken up.
 *
 * It must be called with wq.lock being held.  This spinlock is
 * unlocked while sleeping but @condition testing is done while lock
 * is held and when this macro exits the lock is held.
 *
 * The lock is locked/unlocked using spin_lock()/spin_unlock()
 * functions which must match the way they are locked/unlocked outside
 * of this macro.
 *
 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 * set thus when other process waits process on the list if this
 * process is awaken further processes are not considered.
 *
 * wake_up_locked() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function will return -ERESTARTSYS if it was interrupted by a
 * signal and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible_exclusive_locked(wq, condition)		\
	((condition)								\
	 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, do_wait_intr))

/**
 * wait_event_interruptible_exclusive_locked_irq - sleep until a condition gets true
 * @wq: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq is woken up.
 *
 * It must be called with wq.lock being held.  This spinlock is
 * unlocked while sleeping but @condition testing is done while lock
 * is held and when this macro exits the lock is held.
 *
 * The lock is locked/unlocked using spin_lock_irq()/spin_unlock_irq()
 * functions which must match the way they are locked/unlocked outside
 * of this macro.
 *
 * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag
 * set thus when other process waits process on the list if this
 * process is awaken further processes are not considered.
 *
 * wake_up_locked() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function will return -ERESTARTSYS if it was interrupted by a
 * signal and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible_exclusive_locked_irq(wq, condition)		\
	((condition)								\
	 ? 0 : __wait_event_interruptible_locked(wq, condition, 1, do_wait_intr_irq))


#define __wait_event_killable(wq, condition)					\
	___wait_event(wq, condition, TASK_KILLABLE, 0, 0, schedule())

/**
 * wait_event_killable - sleep until a condition gets true
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 *
 * The process is put to sleep (TASK_KILLABLE) until the
 * @condition evaluates to true or a signal is received.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * The function will return -ERESTARTSYS if it was interrupted by a
 * signal and 0 if @condition evaluated to true.
 */
#define wait_event_killable(wq_head, condition)					\
({										\
	int __ret = 0;								\
	might_sleep();								\
	if (!(condition))							\
		__ret = __wait_event_killable(wq_head, condition);		\
	__ret;									\
})

#define __wait_event_killable_timeout(wq_head, condition, timeout)		\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      TASK_KILLABLE, 0, timeout,				\
		      __ret = schedule_timeout(__ret))

/**
 * wait_event_killable_timeout - sleep until a condition gets true or a timeout elapses
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @timeout: timeout, in jiffies
 *
 * The process is put to sleep (TASK_KILLABLE) until the
 * @condition evaluates to true or a kill signal is received.
 * The @condition is checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * Returns:
 * 0 if the @condition evaluated to %false after the @timeout elapsed,
 * 1 if the @condition evaluated to %true after the @timeout elapsed,
 * the remaining jiffies (at least 1) if the @condition evaluated
 * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was
 * interrupted by a kill signal.
 *
 * Only kill signals interrupt this process.
 */
#define wait_event_killable_timeout(wq_head, condition, timeout)		\
({										\
	long __ret = timeout;							\
	might_sleep();								\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_killable_timeout(wq_head,			\
						condition, timeout);		\
	__ret;									\
})


#define __wait_event_lock_irq(wq_head, condition, lock, cmd)			\
	(void)___wait_event(wq_head, condition, TASK_UNINTERRUPTIBLE, 0, 0,	\
			    spin_unlock_irq(&lock);				\
			    cmd;						\
			    schedule();						\
			    spin_lock_irq(&lock))

/**
 * wait_event_lock_irq_cmd - sleep until a condition gets true. The
 *			     condition is checked under the lock. This
 *			     is expected to be called with the lock
 *			     taken.
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @lock: a locked spinlock_t, which will be released before cmd
 *	  and schedule() and reacquired afterwards.
 * @cmd: a command which is invoked outside the critical section before
 *	 sleep
 *
 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * This is supposed to be called while holding the lock. The lock is
 * dropped before invoking the cmd and going to sleep and is reacquired
 * afterwards.
 */
#define wait_event_lock_irq_cmd(wq_head, condition, lock, cmd)			\
do {										\
	if (condition)								\
		break;								\
	__wait_event_lock_irq(wq_head, condition, lock, cmd);			\
} while (0)

/**
 * wait_event_lock_irq - sleep until a condition gets true. The
 *			 condition is checked under the lock. This
 *			 is expected to be called with the lock
 *			 taken.
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @lock: a locked spinlock_t, which will be released before schedule()
 *	  and reacquired afterwards.
 *
 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the
 * @condition evaluates to true. The @condition is checked each time
 * the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * This is supposed to be called while holding the lock. The lock is
 * dropped before going to sleep and is reacquired afterwards.
 */
#define wait_event_lock_irq(wq_head, condition, lock)				\
do {										\
	if (condition)								\
		break;								\
	__wait_event_lock_irq(wq_head, condition, lock, );			\
} while (0)


#define __wait_event_interruptible_lock_irq(wq_head, condition, lock, cmd)	\
	___wait_event(wq_head, condition, TASK_INTERRUPTIBLE, 0, 0,		\
		      spin_unlock_irq(&lock);					\
		      cmd;							\
		      schedule();						\
		      spin_lock_irq(&lock))

/**
 * wait_event_interruptible_lock_irq_cmd - sleep until a condition gets true.
 *		The condition is checked under the lock. This is expected to
 *		be called with the lock taken.
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @lock: a locked spinlock_t, which will be released before cmd and
 *	  schedule() and reacquired afterwards.
 * @cmd: a command which is invoked outside the critical section before
 *	 sleep
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or a signal is received. The @condition is
 * checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * This is supposed to be called while holding the lock. The lock is
 * dropped before invoking the cmd and going to sleep and is reacquired
 * afterwards.
 *
 * The macro will return -ERESTARTSYS if it was interrupted by a signal
 * and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible_lock_irq_cmd(wq_head, condition, lock, cmd)	\
({										\
	int __ret = 0;								\
	if (!(condition))							\
		__ret = __wait_event_interruptible_lock_irq(wq_head,		\
						condition, lock, cmd);		\
	__ret;									\
})

/**
 * wait_event_interruptible_lock_irq - sleep until a condition gets true.
 *		The condition is checked under the lock. This is expected
 *		to be called with the lock taken.
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @lock: a locked spinlock_t, which will be released before schedule()
 *	  and reacquired afterwards.
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or signal is received. The @condition is
 * checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * This is supposed to be called while holding the lock. The lock is
 * dropped before going to sleep and is reacquired afterwards.
 *
 * The macro will return -ERESTARTSYS if it was interrupted by a signal
 * and 0 if @condition evaluated to true.
 */
#define wait_event_interruptible_lock_irq(wq_head, condition, lock)		\
({										\
	int __ret = 0;								\
	if (!(condition))							\
		__ret = __wait_event_interruptible_lock_irq(wq_head,		\
						condition, lock,);		\
	__ret;									\
})

#define __wait_event_lock_irq_timeout(wq_head, condition, lock, timeout, state)	\
	___wait_event(wq_head, ___wait_cond_timeout(condition),			\
		      state, 0, timeout,					\
		      spin_unlock_irq(&lock);					\
		      __ret = schedule_timeout(__ret);				\
		      spin_lock_irq(&lock));

/**
 * wait_event_interruptible_lock_irq_timeout - sleep until a condition gets
 *		true or a timeout elapses. The condition is checked under
 *		the lock. This is expected to be called with the lock taken.
 * @wq_head: the waitqueue to wait on
 * @condition: a C expression for the event to wait for
 * @lock: a locked spinlock_t, which will be released before schedule()
 *	  and reacquired afterwards.
 * @timeout: timeout, in jiffies
 *
 * The process is put to sleep (TASK_INTERRUPTIBLE) until the
 * @condition evaluates to true or signal is received. The @condition is
 * checked each time the waitqueue @wq_head is woken up.
 *
 * wake_up() has to be called after changing any variable that could
 * change the result of the wait condition.
 *
 * This is supposed to be called while holding the lock. The lock is
 * dropped before going to sleep and is reacquired afterwards.
 *
 * The function returns 0 if the @timeout elapsed, -ERESTARTSYS if it
 * was interrupted by a signal, and the remaining jiffies otherwise
 * if the condition evaluated to true before the timeout elapsed.
 */
#define wait_event_interruptible_lock_irq_timeout(wq_head, condition, lock,	\
						  timeout)			\
({										\
	long __ret = timeout;							\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_lock_irq_timeout(				\
					wq_head, condition, lock, timeout,	\
					TASK_INTERRUPTIBLE);			\
	__ret;									\
})

#define wait_event_lock_irq_timeout(wq_head, condition, lock, timeout)		\
({										\
	long __ret = timeout;							\
	if (!___wait_cond_timeout(condition))					\
		__ret = __wait_event_lock_irq_timeout(				\
					wq_head, condition, lock, timeout,	\
					TASK_UNINTERRUPTIBLE);			\
	__ret;									\
})

/*
 * Waitqueues which are removed from the waitqueue_head at wakeup time
 */
void prepare_to_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
void prepare_to_wait_exclusive(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
long prepare_to_wait_event(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry, int state);
void finish_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_entry);
long wait_woken(struct wait_queue_entry *wq_entry, unsigned mode, long timeout);
int woken_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);

#define DEFINE_WAIT_FUNC(name, function)					\
	struct wait_queue_entry name = {					\
		.private	= current,					\
		.func		= function,					\
		.entry		= LIST_HEAD_INIT((name).entry),			\
	}

#define DEFINE_WAIT(name) DEFINE_WAIT_FUNC(name, autoremove_wake_function)

#define init_wait(wait)								\
	do {									\
		(wait)->private = current;					\
		(wait)->func = autoremove_wake_function;			\
		INIT_LIST_HEAD(&(wait)->entry);					\
		(wait)->flags = 0;						\
	} while (0)

#endif /* _LINUX_WAIT_H */